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Active Site Local Environment Allows Acidic and Basic Synergy in Enzymatic Ester Hydrolysis by PETase
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Atomic-level analysis of PETase enzyme kinetics revealed that high buffer pH improves nucleophilic attack on PET ester bonds while local hydrogen bonding stabilizes the hydrolysis transition state, suggesting two engineering strategies to enhance enzymatic PET degradation. This mechanistic insight directly advances microplastic pollution research by identifying molecular targets for engineering more effective plastic-degrading enzymes capable of breaking down PET microplastics in environmental and industrial settings.
Abstract Polyethylene terephthalate (PET) is a commonly used plastic worldwide and reducing its prevalence is crucial to improving environmental pollution. PETase that degrades PET plastic have received a lot of attention recently. This paper evaluates the ester hydrolysis process under both acidic and basic conditions, and shows that the local environment of the protein active site takes advantage of both. High pH in the protein buffer creates a better nucleophile to attack the ester through a proton shuttle channel in the protein, while local hydrogen bonds to the carbonyl of the ester stabilizes the intermediate/transition state of the hydrolysis reaction. With the understanding at the atomic level, we propose two engineering directions that can potentially improve the reactivity of the PETase: 1) increase the alkaline stability of the protein in general; 2) perturb the local hydrogen bond network to increase the partial charge on the PET carbonyl to be hydrolyzed. Abstract Figure
More Papers Like This
Active Site Local Environment Allows Acidic and Basic Synergy in Enzymatic Ester Hydrolysis by PETase
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This study revealed at atomic resolution how the PET-degrading enzyme PETase exploits both acidic and basic chemistry simultaneously — using high pH for nucleophilic attack while local hydrogen bonds stabilize reaction intermediates — and proposed two engineering strategies to boost its reactivity. These insights advance the development of enzymatic solutions to reduce PET plastic pollution in the environment.
Insights into the Enhancement of the Poly(ethylene terephthalate) Degradation by FAST-PETase from Computational Modeling
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"Researchers used classical and quantum mechanical/molecular mechanics simulations to reveal why the engineered enzyme FAST-PETase degrades PET plastic far more efficiently than its parent enzyme PETase, tracing the enhancement to a single N233K mutation that increases the basicity of a catalytic residue and lowers the energy barrier for the rate-limiting acylation step by over 4 kcal/mol. These findings provide molecular-level design principles for engineering even more effective plastic-degrading enzymes."
The effect of ionic strength on PETase enzymes: an experimental and computational study
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Researchers used molecular dynamics simulations and lab assays to compare two PET-degrading enzymes at different salt concentrations, finding that the marine-derived PETaseSM14 maintains activity under high-salt conditions due to a rigid binding pocket, while the commonly studied IsPETase is deactivated by high ionic strength, offering insights for engineering enzymes suited to diverse environments.
Unveiling the PET plastics degradation potential of the thermostable EstS1 esterase through integrated biochemical, structural, and morphological analyses
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This study characterized the PET-degrading potential of the thermostable esterase EstS1 from an environmental isolate, finding it degrades 75% of BHET (PET's primary intermediate) within one hour, and determined crystal structures showing BHET binding at the active site. SEM imaging demonstrated significant degradation of crystalline PET film over 15 days in controlled and soil-based conditions, with XPS analysis confirming formation of new chemical bonds on the treated surface, supporting potential for dual degradation of plastic and plasticizers.
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Researchers used molecular dynamics simulations to characterize how a cold-active esterase enzyme from Kaistella jeonii changes shape when it binds PET plastic, revealing conformational flexibility in its active site that may explain its ability to break down polyethylene terephthalate at low temperatures.
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